This invention concerns heat sinks of a type widely used for dissipating heat from electronic components by conduction, convection, and radiation.
One configuration of a heat sink is shown in U.S. Pat. No. 5,781,411 comprised of a base plate having an array of tubes projecting from a base plate, with one or more holes drilled in the sidewall adjacent the bottom of each tube, creating a chimney effect by the upward draft of air flow through the tubes.
That heat sink is made by machining material from a molded aluminum piece to form the tubes. This process is relatively costly, which is an important factor for an item produced in vast numbers in the very competitive field of personal computers.
U.S. Pat. No. 5,369,301 discloses a solid pin array integral with a base plate. The pins are formed by forging, but this process can produce only limited height pins, which in turn limits the ability of the structure to function to dissipate heat.
Another drawback of the forging process is that it is difficult to provide varying height pins in an array. It has heretofore been recognized that higher fins or pins at the center of an array may be desirable, as the center area typically tends to be hotter.
It is an object of the present invention to provide an improved method of manufacturing a tube array heat sink and an improved heat sink which allows rapid and economical manufacture, while allowing higher and variable height tubular elements, as well as enabling chimney effect air flow through the tubes.